You should be prompted for a password to unlock the keychain if it is locked. Use your current account password to do so.

This is a temporary workaround.

Another fix submitted by a user

Thanks for the tip! I placed the following wrapper script at /usr/local/bin/mysql-workbench to work around the bug:
#!/bin/sh
if [ -n "${XDG_RUNTIME_DIR}" ]; then
GNOME_KEYRING_CONTROL="${XDG_RUNTIME_DIR}/keyring/control"
[ -z "${GNOME_KEYRING_CONTROL}" ] || export GNOME_KEYRING_CONTROL
fi
/usr/bin/mysql-workbench ${@}